1. Field of the Invention
The present invention relates generally to spherical surfaces and, more particularly, to improved methods for the treatment of spherical surfaces for the purpose of improving their physical and chemical properties. In copending applications of Stephen N. Bunker et al, Ser. No. 167,632, filed Mar. 11, 1988, Group 111, and of Richard W. Oliver, Ser. No. 383,927, filed Jul. 21, 1989, also Group 111, both assigned to a common assignee, Spire Corporation, such improvements in the physical and chemical properties of spherical surfaces are effected by ion implantation.
2. The Prior Art
Ion implantation is a well known method for the surface treatment of metals and compounds, see Treatise on Materials Science and Technology, Vol. 18, "Ion Implantation," 1980, Academic Press, Inc. See also a recently issued U.S. Pat. No. 4,693,760, assigned to the common assignee herein, the Spire Corporation, and entitled "Ion Implantation of Titanium Workpieces Without Surface Discoloration." See further an article authored by M. S. Dresselhaus et al of M.I.T. "Ion Implantation of Polymers," Mat. Res. Soc. Symp. Proc., Vol. 27 (1984), pp. 413-422, and another by G. K. Wolf, "Ion Bombardment Chemistry," Nucl. Instrum. Methods 139 (1976) 147. See also "Ion Beam Modification of Materials for Industry," Thin Solid Films, 118 (1984) 61-71; "The Wear Behavior or Nitrogen-Implanted Metals," Metallurgical Transactions, A 15 (1984), 2221-2229; and "Wear improvement of surgical titanium alloys by ion implantation;" J. Vac. Sci. Tech. A3 (6) Nov./Dec. 1985, 2670-2674.
Inasmuch ion implantation is a line-of-sight process, spherical surfaces represent a geometry that is particularly difficult to ion implant, especially ion implant uniformly about its spherical surface. The uniform ion implantation of spherical surfaces, in particular when needing to process large quantities thereof, has thus presented special problems. The problem has been aggravated even more when wanting to ion implant spherical surfaces of different sizes and of different materials. These shortcomings have been addressed with some success in said copending applications Ser. No. 167,632, filed Mar. 11, 1988, Group 111, of Stephen N. Bunker et al, and of Richard W. Oliver, Ser. No. 383,921, filed Jul. 21, 1989 and assigned to the common assignee, Spire Corporation of Bedford, Mass., the disclosures of both of which are incorporated herein by reference. There is, however, still plenty of room for improvements.
For instance, in addition to exposing the spherical surfaces to an ion beam, the subject, inter alia, of the two aforementioned copending applications, the spherical surfaces also can be surface treated by being exposed to other treatment sources. Some of these treatment sources include sputtering, plasma and pulsed electron beam and light sources, CVD and MOCVD reaction chambers, physical vapor depositions in conjunction with ion beam sources and sputter enhanced ion implantation sources.